黄芩苷改善Aβ_(25-35)诱导的小鼠学习和记忆障碍及可能机制

Baicalin attenuates Aβ_(25-35) induced learning and memory disorders in mice and its possible mechanism

目的观察黄芩苷对Aβ25-35诱导的模型小鼠学习记忆能力的改善作用及对小鼠海马区自噬和自噬相关基因的影响,探讨黄芩苷治疗阿尔茨海默病(AD)的可能机制。方法 C57BL/6小鼠侧脑室注射3μL浓度为3 mmol·L-1的凝聚态Aβ25-35制备AD模型,ip给予黄芩苷25,50和100 mg·kg^(-1),连续给药15 d。通过旷场实验观察小鼠的运动总距离和中央格停留时间,水迷宫定位航行实验观察其潜伏期,空间搜索实验观察原象限停留时间。透射电镜观察海马区自噬小体的生成,Western蛋白印迹法测定中微管结合蛋白1轻链3分子(LC3)和Beclin1的表达。结果脑室注射Aβ25-35可引起小鼠旷场实验运动总距离减少,从(3984±321)cm减少到(2790±306)cm,中央格停留时间由(3.6±1.2)s延长到(8.8±2.9)s,也可使水迷宫实验到达平台总时间由(22.0±1.9)s增加到(38.8±2.2)s;同时观察到海马区早期或晚期自噬泡形成。Western蛋白印迹结果显示,LC3和Beclin1蛋白表达升高(P<0.05)。黄芩苷50和100 mg·kg^(-1)连续给药15 d能延长旷场实验运动总距离,分别为3705±337和(3968±448)cm;中央格停留时间分别缩短为5.6±1.8和(3.9±1.5)s;水迷宫实验到达平台总时间缩短为28.6±1.9和(22.9±1.7)s。透射电镜可见海马区线粒体肿胀,空泡状双层膜结构或者自噬泡形成;LC3和Beclin1蛋白表达明显升高(P<0.01)。结论黄芩苷对AD小鼠的学习记忆损伤有一定的改善作用,作用机制可能与其升高AD小鼠海马区自噬水平有关。

OBJECTIVE To observe the effect of baicalin on Aβ（25-35） induced learning and memory deficits and changes in autophagy-related genes in mice so as to explore the related mechanisms of Alzheimer disease（AD） treatment. METHODS C57 mice were administered with 3 μL Aβ25-353 mmol·L-1by intracerebroventricular injection to establish an AD model. Baicalin was given by intracerebroventricular injection at the dose of 25, 50 and 100 mg·kg-1for 15 d, respectively. The total distance and the central grid residence time were measured in the open-field test. The escape latency and the time to reach the platform were monitored in the Morris water maze trial. The autophagic vacuoles in the hippocampus ofthe mice were observed by transmission electron microscopy before the protein expressions of microtubule-associated protein 1 light chain 3（LC3） and Beclin1 in brain tissue were analyzed by Western blotting assay. RESULTS Intracerebroventricular injection of Aβ25-35 could reduce the total distance from（3984±321）cm to（2790±306）cm and extend central grid residence time from（3.6±1.2）s to（8.8±2.9）s in the open-field test. The escape latency of water maze also increased from（22.0±1.9）s to（38.8±2.2）s.Autophagic vacuoles or late autophagic vacuoles and increased Beclin1 and LC3 and protein level were observed in the hippocampus after Aβ（25-35） injection. Intraperitoneal injection of Baicalin 50 and100 mg·kg-1for fifteen consecutive days extended the total distance in open-field test to（3705±337）cm and（3968±448）cm, respectively, while the central grid residence time was reduced to（5.6±1.8）s and（3.9±1.5）s, respectively. The total time taken to reach the platform in water maze test was reduced to（28.6±1.9）s,（22.9±1.7）s. Mitochondrial swelling, vacuolar membrane structure or autophagic vacuoles were visible in the hippocampus. LC3 and Beclin1 protein expression was significantly up-regulated（P0.01）.CONCLUSION Baicalin shows protective effect against Aβ（25-35） induced learning and memory deficits,and this effect may be related to the activation of autophagy in the mouse hippocampus.